In an engine mounted on a vehicle or similar, a water jacket is disposed on an internal combustion engine (a cylinder head and a cylinder block) as a coolant passage. Cooling water (such as LLC: Long Life Coolant) is circulated through a water jacket by a water pump to cool (warm up) the entire engine.
The water pump of a cooling apparatus for this engine employs a mechanical water pump that increases a discharge amount corresponding to an engine speed. Nowadays, an electric water pump is also used.
In a cooling apparatus of an engine using an electric water pump, the electric water pump is stopped in the case where a water temperature is low, for example, during an engine warm-up operation (at the engine start) so as to stop circulation of the cooling water inside of the engine (inside of the water jacket) (so as to stop the water in the engine cooling system). This accelerates the warm-up of the engine (for example, see Patent Literature 1). In the control for stop of water in the engine cooling system, for example, a temperature of the cooling water inside of the engine is detected or estimated. The stop of water in the engine cooling system ends before the water temperature of the cooling water reaches an overheat temperature of the engine, so as to transit to a water circulation state.